A typical dishwashing process includes manually removing large food particles from soiled dishes using a spatula, tapping the dishes against the side or the edge of a waste container, or other suitable methods. In commercial applications, the operator typically then sprays the soiled dishes with fresh, warm to hot water using a pre-rinse spray hose. In a typical manual pre-rinse operation, the operator uses a commercially available pre-rinse spray hose to spray fresh water onto the soiled dishes, which does not contain any chemicals and is typically at a temperature of between 100 and 120° F. The dishes are then loaded into a dish rack of a dishwashing machine. Optionally, when using a door type, single rack, dishwashing machine, the operator will load the soiled dishes into the dish rack of the dishwashing machine and then use the pre-rinse hose to pre-rinse the dishes. The dish rack is then loaded into the cavity of the dishwashing machine for the automatic wash and rinse operations of the dishwashing machine.
Commercial door type dishwashing machines generally fall into the following four categories: high temperature sanitizing dishwashing machines, chemical sanitizing dishwashing machines, fresh water rinse dishwashing machines, and “dump and fill” dishwashing machines. Many combinations of these categories exist. Wash and rinse times, temperatures, and mechanical action are regulated by NSF standards. In all cases, a portion of the wash and/or rinse water is drained from the machine, either by directly opening a drain mechanism or by using an overflow conduit. The drained water is relatively clean as the water will typically pass through some filtering devices such as screens before reaching the sewer drain. Depending upon the type of dishwashing machine, the temperature of the drained water will typically be between 110 and 150° F., and the water will contain chemicals such as detergent, rinse aid, and sanitizing chemicals.
It is desired to reduce the amount of water and energy used to wash dishes, including the pre-rinse of dishes. Rather than using fresh, heated water in the pre-rinse operation of the dishes, the present invention uses the waste water of the dishwashing machine in the pre-rinse operation of the dishes to reduce the amount of water and energy used to wash dishes.